KR100570322B1 - Method for determining dialysance and device for carrying out the method - Google Patents

Abstract

According to the present method of measuring dialysation of a dialysis machine during external human blood treatment, the concentration of certain substances in the dialysis fluid is changed in the channel of the dialysate upstream of the dialysis machine. The concentration of the substance is changed based on a predetermined starting value and then returned to that starting value. The concentration of material in the dialysate is measured with measuring devices 17, 18 located upstream or downstream of the dialysis machine. The integral of the difference between the outlet concentration of the dialysate over time cdo (t) and the predetermined starting value cdo1 and the inlet concentration between the dialysate over time cdi (t) and the starting value cdi1. The quotient from the integration of the differences is calculated in the evaluation and arithmetic unit 23, and then dialisans are determined based on this calculated quotient and the flow rate of dialysate Qd in the channel of the dialysate.

Description

METHOD FOR DETERMINING DIALYSANCE AND DEVICE FOR CARRYING OUT THE METHOD}

The present invention relates to a method of determining dialysation of a dialyzer during extra corporal treatment of blood and to an apparatus using the method.

The main task of human kidneys is to remove urinary substances that are subsequently released from the blood into the urine, and regulate water and electrolyte release. Hemodialysis is a treatment method that compensates for kidney dysfunction for removing urine from the blood and is used to control the concentration of electrolyte in the blood.

During hemodialysis, blood passes through the dialysis machine's blood chamber in an extra corporal loop, which is separated from the dialysis-liquid chamber by a semipermeable membrane. A dialysate containing a certain concentration of blood electrolyte flows through the dialysate chamber. The substance concentration (cd) of the dialysis fluid corresponds to the blood concentration of a healthy individual. During the treatment, the patient's blood and the dialysis fluid flow along both sides of the membrane, in opposite directions, at predetermined flow rates (Qb, Qd, respectively). The urine material diffuses from the blood chamber through the membrane into the chamber for dialysate, while simultaneously the electrolyte solution present in the dialysate and blood diffuses from the chamber with the higher concentration to the chamber with the lower concentration. The exchange of materials can be further influenced by applying transmembrane pressure.

In order to optimize the blood treatment method, it is necessary to determine the parameters of hemodialysis during blood treatment outside the human body ( in vivo ). Of particular importance is the value of the dialyzer's exchange performance, which is expressed as the so-called clearance or dialisin (D) of the dialyzer.

The virtual (calculated) volume of blood from which per minute specific substances have been completely removed under the conditions defined in the dialysis machine is designated as clearance for the particular substance (K). Dialysates is another term that determines the performance of a dialyzer, taking into account the concentration of the substance discharged into the dialysate. In addition to these parameters, other parameters are also important for describing the performance of the dialyzer, which include values for the aqueous fraction of blood, blood volume, blood input concentration, and the like.

Determination of the above mentioned parameters by measurement and mathematical methods and the quantification of the blood purification process are relatively complex. For the basis of the associated calculations, the alternation of renal function by dialysis {W. Drucker and FM Parsons, JF Meier (publ.) Nijhoff, Den Haag , 1983, in Sargent, JA, Gotch, FA, "Principles of Biophysics of Dialysis."

Dialysates or clearance can be determined as follows for sodium at a given electrolyte, for example the ultrafiltration rate of zero.

Dialysate (D) is the mass transport (Qb x (cbi-cbo)) for these electrolytes on the blood side, and the difference in the concentration of these electrolytes between the blood and the dialysate at the specific input of the dialyzer (cbi- cdi).

Then, to reach mass equilibrium:

Therefore, from the above two equations (1) and (2),

In Equations 1 to 3 above:

Qb = effective blood flow

Qd = flow of dialysate

cb = concentration of substance in the blood

cd = concentration of the substance in the dialysate

i = Input of dialysis machine

o = discharge of dialysis machine

The effective blood flow is the flow of the blood fraction in which the substance to be removed is dissolved, ie this fraction is related to the (liquid) volume of the solution for this substance. Depending on the material, this can be either a plasma water flow or a blood water flow, ie the total water fraction in full blood.

Known methods for the in vivo determination of the parameters of hemodialixis are based on the above described. Since this represents a significant risk source, efforts should be made to deal with it without any direct intervention for the measurement of the blood side. The value to be determined should therefore only be derived from the measurements made on the dialysis side.

The German patent DE 39 38 662 C2 (EP 0 428 927 A1) discloses a method for the in vivo determination of the parameters of hemodialisis, in which the dialysate-electrolyte transport is different at two different dialysis input concentrations. Is measured in the case. Assuming blood input concentrations are constant, according to a known method, dialisan determines that the difference between the dialysate ion concentration on the input side of the dialyzer and the differences in the dialysate ion concentration on the output side is determined at the first and second measurements. Determined; This is divided by the difference in the dialysate ion concentration on the input side during the first and second measurements, and multiplied by the dialysate flow. In this method, a relatively long measurement time is a disadvantage that can be attributed to the fact that after the dialysate has been adjusted to a new input concentration value, an equilibrium stable state must be established at the dialyzer output before the new measured value is recorded. Because of the system-related factors, there will be a specific time for the rapid rise in conductivity at the dialyzer input to be stable at the output of the dialyzer. Moreover, a relatively long time is required for the instrument to be adjusted to a constant value for the dialysate input concentration.

European patent EP 0 272 414 B1 describes a device for determining changes in intravasal blood volume during hemodialysis. In addition to the catheter blood volume, dialysate of the dialyzer is also determined. Although the measurement method used to determine the dialysate is not described in detail, it is proposed that the conductivity measurement should be made on both the blood side and the dialysate side in order to determine the dialysate, and the change in the conductivity on the blood side and the dialysate side Integral is formed through.

Physiology Handbook of Niels A. Lassen, Ole Henriksen, and Per Sejrsen (The Cardiovascular System, Volume 3, Peripheral Circulation and Organ Blood Flow, Part I , American Physiological Association, 1983}, shows that when the problem of signal convolution plays an important role, the mass of the intra corporal circulation loop for injection and subsequent measurement of concentration. Provide a more detailed discussion of the response.

It is an object of the present invention to describe a method which allows for the rapid determination of dialysates during human external blood treatment. A further object of the present invention is to describe an apparatus for this method.

According to the invention, these objects are achieved through the features disclosed in claims 1 or 4 respectively.

In order to determine the concentration (cd) starting from the initial value (cdil), the concentration of a particular substance in the dialysate is changed upstream of the dialyzer (the dialysate input concentration (cdil)) in the dialysate path and then back to the initial value. It is adjusted once again. For example, concentrated masses of hypertonic NaCl solutions that do not affect the dialysis treatment may be added to the dialysate route upstream from the dialysis machine. Thereafter, the concentration of the substance in the dialysate is measured downstream of the dialyzer (dialysis fluid output concentration cdo); This changes starting from a predetermined initial value and then adjusts back to the initial value. If the change in dialysate input concentration is not known about the change in concentration over time, the concentration of the substance upstream from the dialyzer is also measured.

The decision of dialisans is based on the calculation of two integrals, from which the quotient is formed. This quotient is calculated from the integral of the difference between the dialysate output concentration (cdo) and the initial value (cdo1) over time, and the integral of the difference between the dialysate input concentration (cdi) and the initial value (cdi1) over time, Lysans is determined using this share and the predetermined flow rate of the dialysate within the dialysate route. Integration may be performed within relatively narrow limits based on the width of the concentrate bolus.

The advantage is that it is not necessary to set a constant value for the dialysate input concentration. It is sufficient to add the concentrate concentrate relatively uncontrolled into the dialysate feed line.

The input concentration or output concentration of the dialysate is preferably to be determined by measuring the conductivity of the dialysate. It is also possible to use light sensors and other sensors to measure dialysate input or output concentrations in the dialysate path instead of conductivity sensors.

The method according to the invention and the apparatus for the method will be described in more detail below with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic illustration of a device for determining dialysates with key components of a hemodialis device.

2 shows the dialysate input and output concentrations as a function of time.

The device for determining the dialysance (D) of the dialysis machine of the dialysis device may form a separate structural group. This group may be a component part of the dialysis device, especially since some components of the device for determining dialysates already exist in known dialysis devices. Along with the key components of the dialysis device, the device for determining dialysate is described below.

The dialysis apparatus comprises a dialysis machine 1 separated by a semipermeable membrane 2 into a blood chamber 3 and a dialysate chamber 4. The blood supply line 5 enters the inlet of the blood chamber 3 from the patient, and the blood return line 6 enters the patient back from the outlet of the blood chamber 3. The blood pump 7, which establishes the blood flow rate in the extra corporal circulatory system, is coupled with the blood supply line 5.

The inlet of the dialysate chamber 4 is connected to the dialysate source 9 via the dialysate supply line 8, and the outlet of the dialysate chamber is connected to the outlet 11 via the dialysate discharge line 10. A dialysate pump 12 that establishes a flow rate of dialysate in the dialysate path is coupled with a dialysate drain line 10.

The blood pump 7 and the dialysate pump 12 are activated from the central control unit 15 of the dialysis apparatus via control lines 13, 14, which control inputs are used to set the volume delivered by the pump. The unit 16 is provided.

In order to determine the mass concentration of the dialysate at the input of the dialyzer 1 and the mass concentration of dialysate at the outlet of the dialyzer 1, the measuring devices 17, 18 are equipped with a dialysate supply line 8 and a dialysate drainage line 10. Are placed on each. Measuring devices 17 and 18, used to determine the dialysate input and output concentrations cdi and cdo, upstream and downstream from the dialyzer 1, the temperature-corrected conductivity of the dialysate based on the concentration of Na has a conductivity sensor that preferably measures corrected conductivity. The conductivity sensor is connected to the memory unit 21 via data lines 19 and 20. The memory unit 21 receives the measured values from the sensors and stores these values sequentially over time. The measured value is transmitted to the computer and analysis unit 23 via data line 22. The computer and analysis unit receive the flow rate of the dialysate in the dialysate path delivered by the dialysate pump 12 from the central control unit 15 of the dialysis device via data line 24. The display device 26 is connected to a computer and an analysis unit via a data line 25, which shows the dialysian (D) of the dialyzer and, optionally, other parameters of heemodialysis. .

An apparatus 27 for changing the dialysate input concentration cdi is coupled upstream from the dialyzer 1. Using this apparatus 27, it is possible to add concentrated concentrates to the dialysate flowing into the dialyzer, with the result that the Na concentration of the dialysate is increased for a short time upstream from the dialyzer.

Measurements made to determine dialysine (D) are processed via a control unit 28, which includes an apparatus 27 for changing the Na concentration of the dialysate, and a computer and analytical unit 23. It is connected via data lines 29 and 30.

The program stored in the control unit 28 for measuring dialysation D will be described in more detail later.

At the start of the measurement, the dialysate at a predetermined Na concentration flows through the dialysate chamber 4 of the dialyzer 1 at a determined flow rate Qd via the dialysate pump 12. The device 27 now increases the dialysate input concentration cdi (concentrate concentrate) for a short period of time, which is recorded by the conductivity sensor 17 coupled upstream from the dialyzer. The dialysate output concentration cdo set during the dialysis is captured by the conductivity sensor 18 coupled downstream from the dialyzer.

2 shows curves for dialysate input and output concentrations (cdi, cdo) upstream and downstream from the dialyzer. The computer and the analysis unit are configured from the initial values of the dialysate output concentration cdo1 and the input concentration cdi1, that is, the predetermined dialysate flow rate Qd, and the dialysate input and output concentration {cdi (1) according to the following equation (4). , cdo (t)} is calculated from the progression over time:

This calculated dialisan D is then displayed on the device 26. If dialisan D is known, additional hemodynamic parameters, for example blood input concentration cbi, can be calculated using Equation 4 and then displayed.

는 도 2에서 곡선 I 아래에 있는 A 라고 명명된 면적에 해당하는데, 상기 곡선 I은 투석액 입력 농도(cdi)의 시간에 대한 변화를 기술한다. 분자

는 곡선 II 아래의 면적(B)에 해당하며, 상기 곡선 II은 투석액 출력 농도(cdo)의 시간에 대한 변화를 기술한다. denominator

Corresponds to the area labeled A under curve I in FIG. 2, which describes the change over time of the dialysate input concentration (cdi). molecule

Corresponds to the area B under curve II, which describes the change over time of the dialysate output concentration (cdo).

The integration limit will be set such that dialiesan D can be determined with sufficient precision. This integration limit is based on the width of the concentration concentrate.

To simplify this method, an empirical scaling factor for the quotient can be used for the quotients, or for individual integrals to account for system variations caused by, for example, too small integration limits. Can be used separately.

In addition, when ultrafiltration rates UF ≠ 0 and UF >> QB are used, Equation 5 below may be used instead of Equation 4.

The present invention is used to enable the rapid determination of dialisans during human external blood treatment.

Claims (6)

delete delete delete A device for use with a blood processing device, The blood to be processed flows through the blood chamber of the dialyzer in an external circulation loop of the human body, which is separated by the semipermeable membrane into the blood chamber and the dialysate chamber, and the dialysate is in the dialysate path through the dialysate chamber of the dialyzer Flowing in, the dialysate pump to deliver the flow rate (Qd) of the dialysate, Upstream from the dialyzer, the concentration of a specific substance of the dialysate (dialysate input concentration [cdi (t)]) in the dialysate route upstream from the dialyzer is changed starting from a predetermined starting value (cdi1), and the dialysate input concentration is initiated. A device 27 for readjusting the value, A measuring device 18 for measuring the concentration of the substance of the dialysate (the dialysate output concentration [cdo (t)] downstream from the dialyzer; Coupled in the dialysate path with computer and analysis unit 23 to determine the dialysate (D) from the dialysate input concentration [cdi (t)] and the dialysate output concentration [cdo (t)]. In the dialysation determination apparatus of a dialysis machine for use with a blood processing apparatus, The computer and analysis unit 23 is configured to integrate the difference between the dialysate output concentration [cdo (t)] and the predetermined initial value cdo1 for time t and the dialysate for time t. The quotient is calculated from the integral of the difference between the input concentration [cdi (t)] and the initial value cdi1, and the dialysate (D) is the determined quotient and the dialysate in the dialysate path. It is configured to be able to be determined based on the predetermined flow rate (Qd) of the dialyzer determination apparatus of the dialyzer. The dialysis device of claim 4, wherein the measuring device (17) for measuring the dialysate input concentration (cdi (t)) is coupled upstream from the dialyzer. 6. A measuring device as claimed in claim 4 or 5, wherein the measuring device for measuring the dialysate input or output concentration [cdi (t), cdo (t)] is respectively arranged upstream or downstream from the dialyzer within the dialysate path. A dialysis determination device for a catapult, characterized by comprising rate sensors (17, 18).

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